Eliminate unreachable PROC/DEFAULT_VDB GC_printf calls in gctest main()

Eliminate unreachable PROC/DEFAULT_VDB GC_printf calls in gctest main()

* tests/test.c [!GC_WIN32_THREADS && !GC_PTHREADS && !NO_INCREMENTAL
&& (MPROTECT_VDB || PROC_VDB || GWW_VDB) && !MAKE_BACK_GRAPH &&] (main):
Remove unreachable GC_printf call about DEFAULT_VDB; remove extra check
of GWW_VDB case.
* tests/test.c [GC_PTHREADS && MPROTECT_VDB && !REDIRECT_MALLOC
&& !MAKE_BACK_GRAPH && !USE_PROC_FOR_LIBRARIES && !NO_INCREMENTAL]
(main): Remove extra check of MPROTECT_VDB case; remove unreachable
GC_printf calls about PROC_VDB and DEFAULT_VDB.